Party-line ringing-key.



G. P. TROMP.

PARTY LlNE RINGING KEY.

APPLICATION FILED MAR. 26, I915.

1,200,547. Patented Oct. 10,1916.

M/ffnesses;

mr NORRIS rcrsns cav FMOTO-LH'NQ, wnsumumm u c UNITED STATES PATENT OFFICE.

GERARD PIE'IER TROMP, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

PARTY-LINE RINGING-KEY.

Specification of Letters Patent.

Patented Oct. 10, 1916.

Application filed March 26, 1915. Serial No. 17,158.

T all whom it may concern Be it known that I, GERARD PIETER TROMP,

a subject of the Queen of the Netherlands,

residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Party-Line Ringing-Keys, of which the following is a full, clear, concise, and eXact description.

This invention relates to switch keys, and more particularly to party line indicating keys of the mechanically locking type.

The object of this invention is to provide a key structure in which the wear upon the parts comprising the locking mechanism is reduced to a minimum, whereby the life of said parts is greatly prolonged.

In accordance with this invention there is provided a laterally operated latch plate for looking the key plungers in an intermediate position, said latch plate being provided with anti-friction devices for engagement with projections carried by said plungers. The plungers are rotatably mounted in the key frame, which further reduces the wear due to friction between the engaging parts of the latch plate and the plungers by permitting these parts to present new contacting surfaces.

In the drawings illustrating this invention, Figure 1 is a view in side elevation of a key embodying the features of this invention; Figs. 2 and 3 are detailed sectional views taken upon the line 2-2 of Fig. 1, and illustrate the parts of the key in an operated and locked position respectively; and Fig. 4 is a perspective of the latch plate. 'As shown in the drawings, 5 designates a top plate of a switch key having mounted thereon a strip of hard rubber or other suitable insulating material 6. Secured to the top plate 5 is an inverted U-shaped frame 7 upon which are mounted the operating parts of the key. The lower ends of the inverted U-shaped frame are connected by a frame member 8, upon which are mounted a plurality of supporting blocks 9, 9, to each of which are secured spring contact members 10 and 11, each of said blocks also being adapted to receive the lower end of a key metal.

plunger 12, having its upper end extending through the top plate 5. Upon the upper end of each of the key plungers 12 there is mounted a button 13. Formed upon each of the plungers 12 is a conical projection 14E of uniform contour, having a substantially flat upper surface. Secured to each of the plungers 12 is a spring-actuating cam 15 of insulating material also having a uniform conical contour and positioned to actuate contact members 10 and 11 when said plungers 12 are operated to a waydown position.

A latch plate 16, shown in full in Fig. 4:, is preferably stamped from a single piece of Said latch plate is adapted to' be secured to the legs of the U-shaped frame 7, and for this purpose is provided on its opposite ends, adjacent to its lower margin, with projecting members 17, 17 adapted to lie flat against the faces of the legs of said U-shaped frame, and to be pivotally secured thereto. Near the upper margin of the latch plate 16 a plurality of apertures 18, corresponding in number to that of the plungers 12, are provided. These apertures are made by preferably punching out substantially all of the metal of these points, leavinga small U-shaped projecting portion 19 near the conter on each side of said apertures, which projecting portions are afterward bent at right angles to the face of the latch plate. These struck-out projections 19 comprise a supporting means for a rod 20, which carries a plurality of anti-friction rollers 21, positioned intermediate said projections 19 and directly in front of said apertures 18. To prevent the dislocation of the rod 20, the ends thereof are flattened'out, and the ends of each of the struck-out projections 19 are slightly squeezed together. The plate 16 and plungers 12 are mounted in such relation to each other that when a plunger is moved from its normal to intermediate position, the

cam action between projection 14: and the upper portion of the plate will swing the upper edge of the plate away from the remaining plungers. If the movement of the said plunger12 is continued, projection 14 will pass a portion of plate 16 which constitutes the upper boundary of the corresponding opening 18; the plate then returns to its normal position. A further movement of plunger 12 to the operated position causes projection ll to engage the corresponding roller 20, and as a result the upper edge of plate 16 is again moved away from the re maining plungers. The plunger 12 is prevented from returning to its normal position by the engagement of the upper flat surface of projection 14 with the edge of the plate 16 Which constitutes the upper boundary of the opening 18 and the said plunger is thereby latched in the intermediate or indicating position, from which position it may be released by the movement of a second plunger either from its normal to intermediate position, or from its intermediate to operated position.

Near the upper margin at one end thereof the latch plate 16 is provided with an integral arm 25 extending at right angles to the face of the plate to which is attached a laterally projecting roller member 26 adapted, when said plate is in place, to project through a slotted opening in the adjacent leg of the U-shaped frame 7 and engage a spring 27, which spring controls a plurality of spring contacts and also assists in the operation of the key plungers to press the latch plate into engagement with the coacting parts of the plungers 12. Secured in any suitable manner to the frame member 8, on the right-hand side thereof, is a resilient member 28, the free end of which engages the latch plate 16 above its pivotal points, and due to the fact that the tension of said resilient member is in an inward direction, said latch plate is maintained in constant engagement with the plungers 12.

The plungers 12 are freely rotatable so that in the operation of them, new surfaces upon the projections 14 and the spring operating cams 15 are constantly being presented to the anti-friction rollers 21 so that the wear on movable adjacent surfaces is equally distributed. The plungers are normally retained in normal position and re-' turned thereto by means of springs 22.

From the above it will be apparent that the life of a switch key embodying the features described above will be greatly prolonged. The use of anti-friction devices engaging cooperating projections of key plungers and the use of plungers which are free to rotate, thus presenting new operating surfaces, have been found to be of great advantage, inasmuch as they reduce the wearing of engaging parts experienced in other forms of keys.

What is claimed is:

1. In a switch key in combination a frame, a plunger mounted therein, switch springs controlled by said plunger, a swinging latch plate carried by said frame, said latch plate being provided with an aperture, an anti -ed to engage said plunger.

3. In a switch key in combination a frame, a plunger mounted therein, a uniform conical projection formed on said plunger, a swinging latch plate carried by said frame, said latch plate being provided with an aperture, and anti-friction means carried by said latch plate positioned in front of said aperture and adapted to engage said projection on said plunger.

4. In a switch key in combination a frame, a plunger mounted therein, said plunger being free to rotate, a uniform conical projection formed on said plunger, a swinging latch plate carried by said frame, said latch plate being provided with an aperture, and anti-friction means carried by said plate positioned in front of said aperture and adapted to engage said projection on said 5 plunger.

5. In a switch key in combination a frame,

a plunger mounted therein, switch springs controlled by said plunger, a locking projection on said plunger, a swinging latch plate carried by said frame, means struck out of said latch plate and adapted to cooperate with said locking projection, and anti-friction means carried by said plate adapted to engage said plunger.

6. In a switch key in combination, a frame, a plunger mounted therein, said plunger being free to rotate, a uniform conical locking projection formed on said plunger, a swinging latch plate carried by said frame, said latch plate being provided with an aperture adapted to cooperate with said projection, and anti-friction means carried by said plate and adapted to engage said projec-- tion on said plunger.

7. A latch plate for switch keys comprising a metallic plate provided with a plurality of apertures, antifriction means positioned in front of each of said apertures, and a common support for said means carried by said plate.

8. A latch plate for switch keys comprising a metallic plate provided with a plurality of anti-friction devices, a rod on which said devices are mounted and a plurality of struck-out projections formed on said metallic plate and supporting said rod.

9. A latch plate for a switch key comprising a metallic plate provided with a plurality of apertures, a plurality of struckmy name this 25th day of March A. 1)., 1915.

GERARD PIETER TROMP.

and a rod on which said devices are mount- 5 ed, said rod being supported by said struckout projections.

In Witness whereof, I hereunto subscribe Copies of this patent may be obtained for Witnesses: 4

E. EDLER, K. L. STAHL.

five cents each, by addressing the Commissioner of Patents. Washington, D. G. 

